What is condition for the production of sound?

Q.1 what’s necessary condition for the assembly of sound?

Ans. Sound is made by moving bodies. thanks to vibration of bodies the air around them conjointly vibrates. These air vibrations manufacture sensation of sound in our ear. Sound travels within the medium from one place to a different within the variety of compression waves.

Q.2. Justify with the assistance of AN experiment that sound is made by moving bodies.

Ans. Strike the implement against a rubber pad. The implement can begin to vibrate. we are able to feel the-vibrations by slightly touching one in every of the prongs of the moving implement with a plastic ball suspended from a thread. The implement can push the ball thanks to its vibrations. Similarly, if a moving implement is unfit into a glass of water, we are going to see a splash.

Q.3. Justify with the assistance of AN experiment that sound need material medium for its propagation.

Or However are you able to prove the mechanical nature of sound by an easy experiment?

Ans. Place a protection on the platform of a pump. Suspend an electrical bell within the protection with the assistance of 2 wires connected to an influence offer. once the ability offer is switched ON, the electrical bell –will begin ringing. we are able to hear the sound of the bell. currently pump out air from the jar by means that of a pump. once more start the ability offer. The sound of the bell isn’t detected, though the bell is ringing. once we place the air back to the jar, we are able to hear the sound of the bell once more. From this, we have a tendency to conclude that sound will solely travel through a fabric medium.

Q.4. what’s the result of medium on the speed of sound. during which medium sound travels additional faster: air, solid or liquid?

Ans. Sound waves will pass solely by any medium. It cannot labor under vacuum. However, the character of the medium can have an effect on the speed of the sound waves. In general, the speed of sound in an exceedingly liquid is 5 times that in gases; the speed of sound is solid is concerning fifteen times that in gases. The speed of sound in air is full of changes in some physical conditions like temperature, pressure and humidness etc. The speed of sound in solids and liquids is quicker than in air.

Q.5. What does one perceive by the longitudinal waves? Describe the longitudinal nature of sound waves?

Ans. LONGITUDINAL WAVES

Longitudinal waves ar made thanks to compressions and rarefactions. In these waves, particles of the medium withdraw and forth on the direction of propagation of the wave.

Longitudinal Nature of Sound Waves

The waves made by a moving implement ar longitudinal waves. Before the vibration of implement, density of air molecules on the correct facet is uniform (Fig.10.3-a) once the correct projection of implement moves kind mean position O to B (Fig.11.3-b), it exerts some pressure on the adjacent layer of air molecules and produces a compression. This compressed gas layer successively compresses the layer next to that and then on. a flash later, the projection begins to maneuver from B towards A (Fig.1!3-c). currently the pressure within the adjacent layer decreases and a concentration is made. This concentration is transferred to the air layer next to that and then on. because the implement moves back and forth apace, a series of compressions and rarefactions ar created within the air. during this manner, wave propagates through the air. because the direction of propagation of wave is on the direction of periodic air molecules, thus this shows the longitudinal nature of sound waves.

Q.6. Sound may be a variety of wave. List a minimum of 3 reasons to support the thought that sound may be a wave.

Ans. Like waves, sound {is conjointly|is additionally} made by moving bodies and it also transfers energy and exhibits the development of

reflection
refraction
diffraction thus, sound may be a variety of wave.
Q.7. will sound manifest the development of reflection, optical phenomenon and refraction?

Ans. Yes! Sound manifests the development of reflection, optical phenomenon and refraction.

Q.8. what’s the distinction between the loudness and intensity of sound? Derive the relation between the 2.

Ans. LOUDNESS

It is the characteristics of sound by that loud and feint sounds will be distinguished.

INTENSITY OF SOUND –

Sound energy passing per second through a unit space command perpendicular to

Solid direction of propagation of sound waves is termed intensity of sound.

Unit: The SI unit of intensity of sound is watt per area unit (Wm ).

TaWeH.2

 

Sources of Sound

 

Intensity (WnT2)

 

Intensity level (dB)

 

Nearby jet airplane

 

103

 

150

 

Jackhammer / Fast

 

101

 

130

 

Train Siren

 

10°

 

120

 

Lawn mover

 

10^

 

100

 

Vacuum cleaner

 

1CT5

 

70

 

Mosquito buzzing

 

io-8

 

40

 

Whisper

 

to-9

 

30

 

Rusting of leaves

 

io~11

 

10

 

Faintest audible

 

ft *5

 

 

 

sound i.e. Threshold

 

10~12

 

0

 

 

Relation Between Loudness and Intensity of Sound

The loudness (L) of a sound is directly proportional to the exponent of intensity.

i.e. L oc log I

or L=Klogl …… (1)

where K is constant of quotient.

Let L0 be the loudness of the faintest sounding sound of intensity I0 associated L be the loudness of an unknown sound of intensity one, then by Eq. (1), we will write

L0 = KlogI0 …… (2)

Subtracting atomic weight. (1) from atomic weight. (2), we get

L-L0 = KlogI-Klogl0 = K (log one – log 10) Since ( log a – log b – log t), therefore

L-L0=Klogf

Equation (3) exhale relation between loudness and intensity of sound.

Q.9. What does one mean by the term strength of the sound. Name and outline the unit of strength of sound.

Ans. strength

The distinction between the loudness of the faintest sounding sound and also the loudness of associate unknown sound is termed strength or sound level of the unknown sound. •

From Eq. (3), the strength of associate unknown sound is given by

Sound level = K logr- …… (1)

Unit: The SI unit of strength or sound level is bel.

Note: bel could be a terribly massive unit of strength of a sound. Generally, atiny low unit referred to as sound unit (dB) is employed. One bel is capable ten dB.

Q.10. What area unit the units of loudness? Why we tend to|can we|will we} use scale to explain the vary of the sound intensities we hear?

Ans. The unit of loudness is bel or sound unit. as a result of human earxan hear big selection of intensities, mensuration sound strength on a linear scale isn’t convenient for USA. Hence, rather than linear scale, scale is employed for this purpose. for instance; if the sounding intensity vary is measured on a ruler, the dimensions would extend from one foot (faintest) to on top of 3000 miles (loudest).

Q.11. On what factors will loudness of sound depends? justify.

Ans. Loudness of sound depends upon the subsequent factors:

Amplitude of the moving body.
Area of the moving body.
Distance from the moving body.
Amplitude of the moving Body

The loudness of the sound varies directly with the amplitude of the moving body. for instance, the sound created by the star are loud if we have a tendency to pluck its wires a lot of violently. Similarly, after we beat a drum forcefully, the amplitude of its membrane will increase and that we hear a loud sound.

Area of the moving body

The loudness of sound conjointly depends upon the world of the moving body. For example, sound created by an oversized drum is louder than that of atiny low one. Similarly, if we have a tendency to strike a implement on a rubber pad, a feeble sound wilt be detected. But>if the moving implement is placed vertically on the surface of a bench, we’ll hear a louder saund. , Distance from the moving Body

Loudness of sound conjointly depends upon the space of the moving body from the observer, it’s caused by the decrease in amplitude because of increase in distance.

Q.12. what’s distinction between frequency and pitch? Describe their relationship diagrammatically.

Ans. FREQUENCY

The number of vibrations per cycle of a moving body is one second is termed its frequency. PITCH

It is the characteristic of sound by that we will distinguish between a shrill and a grave sound.

The pitch of a sound depends upon the frequency of the sound. a better pitch means that a better frequency and vice, versa. The relation between frequency and pitch of sound is illustrated

Q.13. Describe ihe impact of modification in amplitude on loudnes* and also the impact of modification in frequency on pitch of sound.

Ans. impact OF AMPLITUDE ON LOUDNESS

The loadness of the sound varies directly with the amplitude of the moving body Examples

The sound created by a stringed instrument are loud if we have a tendency to pluck its wires a lot of violently.
When we beat a drum forcefully, the amplitude of its membrane will increase and that we hear a loud sound.
EFFECT OF FREQUENCY ON PITCH

A higher frequency means that a better pitch and’vice versa (Fig. 11.5).

For example, the frequency of the voice of girls and kids is on top of that of men. Therefore, the voice of girls and kids is shrill and of high frequency.

Q.14. If the pitch of sound is exaggerated, what area unit the changes within the following? (a) the frequency

(b) the wavelength

(c) the wave rate

(d) the amplitude of the wave.

Ans. (a) If the pitch of sound is exaggerated, its frequency can increase.

(b) If the pitch of sound is exaggerated, its wavelength can decrease.

(c) If the pitch of sound is exaggerated, the wave rate will increase.

(d) If the pitch of sound is exaggerated, the amplitude of the wave can stay unchanged.

Q.15. will loudness of sound depends upon the wholeness of the rare of the listener?

Ans. Yes, loudness of sound conjointly depends upon the wholeness of the ears of the observer. A sound seems louder to an individual with sensitive ears than to an individual with defective ears.

Q.16. Is there any characteristic of sound that doesn’t rely upon the sensitivity of fhe ears of the listener?

Ans. Yes, there’s a characteristic of sound that doesn’t rely upon’the sensitivity of the ears of the observer and it’s referred to as intensity of sound.

Q.17. what’s meant by echo? will we have a tendency to justify however will this happen?

Ans. ECHO

When sound is incident on the surface of a medium, its bounces into the primary medium. This development is termed echo.

When we clap or shout close to a tall building or a mountain, we’ll hear constant sound once more a bit later. This sound that we have a tendency to hear could be an echo and is a results of reflection of sound.

The sensation of sound persists in our brain for regarding zero.1s. to listen to a transparent echo, the amount between our sound and also the mirrored sound should be a minimum of

0.1s. If we have a tendency to contemplate speed of sound to be 340 ms~1 at a standard temperature in air, we’ll hear the echo when zero.1s. the whole distance lined by the sound from the purpose of generation to the reflective surface and back ought to be a minimum of

340 ms’1 x zero.1s = 34.0 m. Thus, for hearing distinct echoes, the minimum distance of the obstacle from the supply of sound should be 1/2 this distance, that is, 17m. Echoes is also detected quite once because of sequent or multiple reflections.

Q.18. however are you able to notice the speed of sound by echo method?

Ans. mensuration SPEED OF SOUND BY ECHO technique

Apparatus: mensuration tape, stopwatch, flat wall which will manufacture a decent echo.

Procedure

Use the tape to live a distance of fifty metres from the wall.
Now clap your hands before of the wall at a distance of fifty metres associated check if you’ll clearly hear an echo from the wall. confirm that echo isn’t
coming from the other enclose the world. The time taken by the sound to travel one hundred metres is that the time distinction between the clap and also the echo.

Now restart the applause and begin the timer at the primary clap. Count the quantity of claps, and stop the applause and also the timer once you hear the echo of the tenth clap (say).
Now notice the common time for ten claps. when scheming the amount t between claps and victimization the formula s = v t, we will calculate the speed of the sound.
Q.19. Differentiate between noise and musical sounds. conjointly offer examples.

Ans. MUSICAL SOUNDS

Such sounds that am pleasant to our ears area unit referred to as musical sounds. Examples

The sounds created by musical instruments like flute, harmonium, violin, drum, etc. area unit musical sounds.

NOISE

Such sounds that have jarring and ugly impact on our ears area unit referred to as noise.

Examples

The sounds of significant machinery, the slamming of a door, significant traffic, rattling of wheels on the road area unit noise.

Q.20. justify that noise could be a nuisance.

Ans. Noise is associate undesirable sound that’s harmful for health of human and alternative species. Noise has negative effects on human health because it will cause condition like hearing impairment, sleep disturbances, aggression, by pretension, high stress level. Noise may also cause accidents by busybodied with communication and warning signals.

Q.21. however will pollution be reduced?

Ans. pollution are often reduced by substitution the clamant machinery and equipments, golf stroke sound-reducing barriers, or victimization hearing protection devices.

Q.22. what’s meant by acoustic protection. what’s its importance?

Ans. ACOUSTICS PROTECTION

The technique or technique wont to absorb undesirable sounds by soft and porous surface is termed acoustic protection.

Importance of Acoustic

Reflection of sound is a lot of distinguished if the surface is rigid and sleek, and fewer if the surface is soft and irregular. Soft porous materials, like draperies and rugs absorb great deal of sound energy and therefore quiet echoes and softening noises. therefore by victimization such materials in clamant places, we will scale back the extent of pollution. However, if the surface of “classrooms or public halls area unit too absorbent, the sound level is also low for the audience.

Q.23. what’s meant by sounding frequency vary? will this range vary with the age of people? justify.

Ans. sounding FREQUENCY vary

The vary of the frequency that an individual’s ear will hear is termed sounding frequency vary.

A normal human ear will hear a sound as long as its frequency lies between twenty rate to twenty,000 Hz. In alternative words, an individual’s ear neither hears a sound of frequency but twenty rate nor a sound of frequency quite twenty,000 Hz. totally different|completely different} individuals have different vary of audibleness. It conjointly decreases with age. young kids will hear sounds of twenty,000 rate however previous individuals cannot hear sounds even on top of fifteen,000 Hz.

Q.24. what’s ultrasound or ultrasonic?

Ans. ULTRASOUND

Sounds of frequency on top of twenty,000 rate that area unit inaudible to traditional human ear area unit referred to as ultrasound or supersonic.

Q.25. What area unit the uses of ultrasound in medicine?

Ans. SOME USES OF ULTRASOUND IN drugs

In the medical field, supersonic waves area unit wont to diagnose and treat completely different aliments. For identification of various diseases, supersonic waves area unit entered/ into the physique through transmitters, these waves area unit mirrored by completely different organs, tissues or tumors etc. The mirrored waves area unit then amplified to make a picture of the inner organs of the body on the screen. These pictures facilitate in sleuthing the defects in several organs.
Powerful ultrasound waves area unit wont to take away blood clots fashioned within the
arteries.

High intensity ultrasound waves area unit use to destroy germs and bacterium in liquids.
Q.26. however is depth of water measured by echo method?

Ans. Ultrasound is employed to find underwater depths or is employed for locating objects lying deep on the sea bottom, etc. The technique is termed navigational instrument, it stands for sound navigatidn and go. The sound waves area unit sent from a transmitter, and a receiver collects the mirrored sound. The time-lapse is calculated. Knowing the speed of sound in water, the space of the thing from the ocean surface are often calculable.

Q.27. however area unit Cracks detected within the interior of moving components of high speed significant machines?

Ans. Cracks seem in ihe interior of moving components of high speed significant machines like turbines, engines of ships and airplanes because of excessive use. These cracks don’t seem to be visible from outside however they’ll be terribly dangerous. Such cracks are often detected by supersonic. a robust beam of ultrasound is formed to undergo these defective components. whereas passing, these waves area unit mirrored by the surface of those cracks and flaws. The comparison of the supersonic waves mirrored from cracks and from the surfaces of those components will provides a clue of the existence of the cracks.

SOLVED info

Q.1 justify however sound is created by a college bell?

Ans. once hammer strikes the college bell, it starts moving and therefore produces sound.

Q.2 Why area unit sound waves referred to as mechanical waves?

Ans. Sound waves travel within the sort of compressions and rarefactions because of the vibrations of the particles of the medium regarding their mean positions. In alternative word sound waves need material medium for his or her propagation and therefore area unit referred to as mechanical waves.

| Q.3 Suppose you and your friend area unit on the moon. able to} be able to hear any sound created by your friend?

Ans.As there-is no material medium on the moon for the propagation of sound waves, therefore we have a tendency to cannot hear any sound created by our friend on the moon.

Q.4 Why the voice of ladies is a lot of shrill than that of men?

Ans. Voice-of girls is a lot of shrill than that of men because of high frequency and pitch.

Q.5 that property of sound waves determines its (a) Ioudness (b) pitch? Ans.(a)Amplitude of acoustic wave determines its loudness

(b) Frequency of acoustic wave determines its pitch.

Q.6 What would happen to the loudness of sound with increase in.its frequency?

Ans.Loudness of sound doesn’t rely upon the frequency of sound.

SUMMARY

Sound is created by a moving body.

Loudness could be a characteristic of sound by that a loud and a faint sound are often distinguished.

Loudness depends upon the amplitude, extent and distance from the moving body.

Sound energy flowing per second through unit space command perpendicular to the direction of sound .waves is termed the intensity of sound:

bel is unit of the strength of sound, wherever one bel = ten sound unit (dB).

Pitch of the sound is that the characteristic of sound by that a shrill sound are often distinguished from a grave one:

Pitch of Sound depends upon the frequency.

The characteristic of sound by that 2 sound waves of same loudness and pitch area unit distinguished kind one another is termed the standard of sound.”

The sounds with jarring impact on our ears area unit referred to as noise and also the sounds having pleasant impact on our ears area unit referred to as musical sounds.

if The technique or technique wont to scale back the loss of sound energy by a soft

and porous surfaces is termed acoustic protection

Audible frequency vary lies between twenty rate to twenty,000 Hz.

Sound waves of frequency on top of twenty,000 rate area unit referred to as ultrasound or

ultrasonic.

Sound waves of frequency less than twenty rate area unit referred to as infrasound.

Ultrasound is additionally wont to find underwater depths or for locating objects

lying deep on the sea bottom. The technique is termed navigational instrument, short for sound navigation and go.

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